Anti-HMGCR myopathy is an increasingly recognized immune-mediated necrotizing myopathy. However, there are currently no evidence-based treatments available, so case reports and clinical experience are used to guide current management. We report a case of a 49-year-old man, treated with atorvastatin, who presented to the emergency department with progressive proximal muscle weakness. Anti-HMGCR antibodies were detected, and muscle biopsy revealed necrotizing myopathy. Initially, therapy with high-dose glucocorticoids and methotrexate was started, but 12 weeks later, the patient developed clinical deterioration with dysphagia. Then, he was successfully treated with one cycle of rituximab along with physical therapy. The use of rituximab in immune-mediated necrotizing myopathy has been heterogeneously described in the literature but mostly in case reports. The European Neuromuscular Centre working group recommends the use of rituximab in refractory cases. However, some studies highlight the importance of early and aggressive treatment for this disease. Clinical prospective studies are necessary to make proper evidence-based recommendations.